Fuel injection system



May 30, 1961 F. A. SCHICK 2,936,291

FUEL INJECTION SYSTEM Filed July 9, 1957 2 Sheets-Sheet 1 WWW) y 30, 1961 E. A. SCHICK 2,986,291

FUEL INJECTION SYSTEM Filed July 9, 1957 2 Sheets-Sheet 2 J/vwmban @WWQ JQL g M Mfmay United States Patent FUEL INJECTION SYSTEM Frederick A. Schick, Springfield, Ill., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Filed July 9, 1957, Ser. No. 670,718

12 Claims. (Cl. 214-431) This invention relates to a fuel injection system for an internal combustion engine used in tractor vehicles. More particularly the invention is concerned with an improved fuel regulating device which is responsive directly to the load requirement to automatically permit additional fuel to be delivered to the engine in order to minimize an engine overload condition.

It is well known that diesel engines under overload conditions are able to efficiently burn an additional quantity of fuel beyond the normal maximum fuel limit which 'will effectively increase the torque output of the engine and thereby improve its lugging power. This phenomenon is principally due to the increased volumetric efficiency of the engine at a somewhat lower engine speed. Heretofore, several fuel regulating devices for fuel injection systems have been suggested which permit additional fuel to be delivered to the engine to minimize the tendency to stall under overload conditions. These conventional devices, however, have not been entirelysatisfactory for all diesel engine applications, For example, in a tractor mounted shovel loader application, it is oftentimes desirable to lift a heavy load with the shovel, thereby taxing the engine driven hydraulic pump to its maximum limits, and simultaneously propel the tractor forward against a considerable resistance such as into the material being excavated or handled thereby substantially increasing the so-called drawbar load on the engine. The combined horsepower requirements of the hydraulic pump together with the drawbar load oftentimes places the engine under a considerable, although momentary, overload. Most conventional fuel regulating systems incorporate a governor device having spring load mechanical linkages which rely upon engine speed for adjusting the position of the fuel control linkage. In some conventional systems the stop mechanism for the fuel control linkage is adjusted by mechanical linkages responsive to engine speed in order to permit additional movement of the linkage and increase the amount of fuel to be de livered by the fuel pump to the-engine under overload conditions. The operation of these devices is such that unless the engine speed is reduced substantially the fuel controls will not be fully opened thereby affording only a small power increase. Also, there-is a considerable time lag from the instant the overload is placed upon the engine until the mechanical linkages are adjusted to permit additional fuel delivery. During the shovel loader operation, for instance, the overload demand is momentary and with present fuel control systems the time lag in delivering the addition fuel results in insuflicient power increase causing sluggishness of operation and poor response.

In still other conventional systems, the governor device is overruled and the maximum fuel stop position is adjusted by the operator to permit additional fuel delivery under engine overload conditions. It will be readily understood, however, that the operator has plenty to do without being required to hand operate such a device to get the maximum advantage from the engine.

Patented May 30, 19 61 It is, therefore, an object of the present invention to provide an improved fuel injection system which will overcome the difficulties hereinbefore described in an entirely satisfactory manner. 7 t

It is another object of the present invention to provide a fuel injection system in which the fuel control device is directly responsive to load requirements to automatically supply additional fuel to minimize the effects of an engine overload condition.

It is another object of the present invention to provide a fuel injection system for an engine in a tractor vehicle of the type having a hydraulic system to operate tractor mounted tools wherein the fuel control device is responsive to the load requirements of the hydraulic system to automatically supply additional fuel to minimize an engine overload condition.

It is another object of the present invention to provide an improved fuel regulating device for a fuel injection system on an engine in a tractor vehicle of the type having a hydraulic system to operate tractor mounted tools wherein the fuel regulating device includes a pressure sensitive means which is responsive to a predetermined load pressure within the hydraulic system to adjust the maximum fuel stop member thereby permitting the fuel control linkage to increase the fuel supply so as to minimize an engine overload condition.

These and other objects and advantages will become apparent to those skilled in the art from the following detailed description when it is read in conjunction with the annexed drawings wherein:

Fig. 1 is a schematic partial section view of a fuel regulating device in side elevation having the housing cut away showing the components of a centrifugal type governor; a pressure sensitive means being shown in section illustrating the position of the various parts; and the principal components of the hydraulic system for the tractor being shown diagrammatically in partial section.

Fig. 2 is a view in side elevation of a crawler tractor equipped with a front end shovel attachment wherein some of the parts of the tractor are broken away to illustrate the position of the fuel injection and hydraulic systems.

Referring to Fig. 2, a crawler tractor 6 of conventional design having a main frame 4 supporting an engine S'and being equipped with a front end shovel attachment 7 also of conventional design. The shovel attachment 7 comprises a support 8 secured on the main frame of the crawler tractor at opposite lateral sides. A pair of main boom members 9 are pivotally connected respectively at one end to support 8 by pivot means 11 and extend forwardly of the crawler tractor. booms 9 are pivotally connected by pivot means'12 to the rear portions of the shovel or bucket 13. A pair of hydraulic jacks 14 are interposed respectively between the booms 9 and the support 8 at opposite lateral sides of tractor 6 for raising and lowering the shovel 13 and having their opposite ends pivotally connected respectively to booms 9 and support 8. A pair of arms 17 are pivotally connected, respectively, at one of their ends to the upper rearward portion of bucket 13 and their opposite ends respectively being pivotally connected to a pair of links 18 which in turn are pivotally connected respectively to boom members 9. A pair of hydraulic jacks 19 respectively interconnect the links 18 and the support 8 at opposite lateral sides of the trtctor 6 for the purpose of tilting the bucket 13 about the pivot means 12.

Referring now to Figs. 1 and 2, the control valve mechanism 21 is of conventional design and construction and includes hand levers 22 which can be selectively operated to adjust the main valve 23 permitting hydraulic fluid to be delivered to the pairs of hydraulic jacks 14 and 19 thereby controlling operation of the bucket 13.

The opposite ends of in the usual manner. 1311565 a fuel injection pump of either the single or multiaxial movement thereon.

sesame 1 The hydraulic system 24 includes areservoir26-for-hydraulic fluid, an engine-driven hydraulic pump 27, con- 'dllit means 28 interconnecting the'reser'voir 26 and the pump 27, conduit means 29 interconnectingthe delivery sideof the pump 27 with the control'valve-mechanism 21, conduit means 31 interconnecting the control valve mechanism with the hydraulic motors or jacks, and a bypass conduit 32 interconnecting the valve mechanism 21 and the reservoir 26. In other words system 24 serves a's a hydraulic motor system for operating the tractor tool 7.

A fuel injection system 36 is mounted on the engines The fuel injection system 36 complunger type represented generally in-Fig. 2 by reference character 37 which is adapted to be-'associated with the engine in conventional manner and a fuel regulating device 38 to be connected to the fuel injection pump 37.

As best shown in Fig. 1, the fuel regulating'device 38 includes a conventional centrifugal 'flyball governor 39 "having a housing 41'which is rigidly-conne'cted to the injection pump housing 37 (in Fig. 2). and operation of the governor 39 is generally well understood therefore only the coaction of the components 'which are pertinent to carrying outthe inventionwill be The construction described. A governor shaft 42 is jonrnaled on the housing 41 and is mounted in-driven relationship to fuel injection pump shaft 43 which in turn is driven'by the 1 engine 5. A spider 44 is mounted on the shaft "42 for rotation therewith and carries a plurality of governor *weights or fiyballs 46 which are pivotally mountedth'ereon as by roller bearings. '47 which is in thrust transmitting contact with an'end "plate 48 presented by the flanged end 49 of 'a'sleevemem- Each weight'46 has an arm ber -51 which is journaled on the governor shaft42 for Governor springs 52 are 'carried on the governor shaft 42 and are operatively interposed between a collar portion 53 of the sleeve 51 and the retaining cap 54 which is secured to the housing 41.

A linkage means 56 includes a link member or fulcrum lever 57 having a bifurcated end which is pivotally mounted on the collar 53 by pins 59, and a control rod or lever 61 of the fuel injection pump 37,-one end of which is pivotally mounted by pin 62'adjacent one end of the fulcrum lever 57 and the opposite end being engageable with the plunger (not shown) on thefuel pump 37 in order to control the quantity of fuel being delivered to the engine 5. On one end of the fulcrum lever 57 is attached a smoke limit cam 63, and the opposite end is pivotally connected to a crank arm 64 by pin 66 which is nonrotatably mounted on a shaft 67. Shaft 67 is'to'be journaled in the housing 41 having a lever-arm 68 (shown in Fig. 2) nonrotatably attached on its opposite end. A linkage means 69 (shown in Fig. 2) interconnects the lever arm 68 and a manually actuated throttle lever 71 (shown best in Fig. 2). Upon selective adjustment of the throttle lever 71, the crank arm 64 is pivoted in either a clockwise or counterclockwise direction thereby pivoting the fulcrum lever 57 about pin 59 which in turn moves the control rod 61 either to the left or rightso as to the outside of housing 74 a longitudinally extending bore 77 is provided in three steps by a first section 78, a second section 79 and a third section 81. The first section 78 of bore 77 is threaded to receive a fitting'82. The fitting '82 has a threaded portion 83in engagement with here fluid tightconnection.

78, an axially extending bore 84 which is in two sections 86 and 87, a circumferentially extending groove 88 and a diametrically extending bore 89 in groove 88 which intersects with axial bore 84. A first section 86 of bore 84- begins at the head 91 of fitting 82 and extends axially terminating at the intersection with bore 89 and a second section 87, smaller than the-first, begins at the intersection with bore-89 and extends axially through the end of the fitting. A plug 92 is in threaded engagement with the-end of section 86 of bore 84 at the head 91. Upon removal-of plug 92 air-maybe bled out of the hydraulic system. A bushing member 93 is carried on the fitting S2 in overlying relationship to groove 83 forming a circumferential passageway 90. A pair of washers 94 and 96 are also carried respectively on the fitting 82 at each axial end of the bushing 93, washer 94 being interposed between the head 91 and the bushing 93 and washer 96 between the bushing 93 and the outside portion of the housing 74 which surroundsbore 77 so as to provide a A conduit 97 is connected at one endto bushing 93 by means of a pressure fitting 98 which is in threaded engagement with a bore 99 provided in bushing 93 and communicates with passageway 90. Conduit 97 at the opposite end is connected into conduit 29 at'a-point which is between the delivery side of hydraulic pump-27"and the valve control mechanism 21 thereby establishing fluid communication between the pressure sensing means 73 and the hydraulic system 24 through two adjusting nuts 106. A'spring 107 is carried on shank 104be'aring'at one end against a shoulder 108 andat the'other end against head 103 thereby urging the out- 'side portion of head 103 against the end of fitting 82.

A pin'or piston element 109-is reciprocably mounted in the pressure cylinder defined by section "87 of bore 84.

One end of pin element 109'presents an area on which the hydraulic flu'idacts, and the opposite end is in thrust transmitting contact with head 103 of bolt 102. The

leftward travel of stop member 101 is limited to a predetermined distance by adjusting screw 111 which is threaded into housing 74. Head 112 of screw 111 is 'enga'geable by the end of bolt 102. Screw 111 is adjustable axially being fixedly held in place by lock nut 113 which is in threaded engagement therewith. Since stop "plate 72 is'engageable by the cam 63 of the'fulcrum lever 57 to limit leftward movement of the linkage means 56, any movement to the left of the stop member 101 would tend to permit'additional movement to the left of control rod 61 thereby increasing the quantity of fuel to be delivered by the fuel injection pump 37.

Operation The engine speed range is manually adjusted in the conventional manner by means of the throttle lever 71 as follows: if it is desired to increase engine speed, the lever 71 is'adjusted so as to rotate arm 68 and shaft 67 counterclockwise (as viewed in Figs. 1 and 2) causing crank arm 64 to rotate upwardly and to the right pivoting the fulcrum lever 57 about pin 59 in a counterclockwise direction thereby urging the control rod 61 to the left to increase the amount of fuel to be delivered by the fuel pump 37 to the engine 5. As the engine speed is increased, the speed of the governor shaft 42 is corresporidingly increased which causes the governor weights 46 to be'moved outwardly by centrifugal force. As the weights move outward the arms 47 are thrust against the end plate 48 of flange portion 49 tending to slightly move the sleeve member 51 toward the right against the opposition of the"governor spring 52. The movement of the 14 to raise a load.

sleeve member 51 tends to pivot the fulcrum lever 57 to the right about pin 59 which simultaneously moves the control rod 61 to the right he direction to decrease the amount of fuel delivered to engine 5, thus establishing the adjusted engine speed corresponding to the position of the throttle lever 71 under no engine load condition. If it is desired to adjust the speed range to decrease the engine speed, the lever 71 is moved in the opposite direction and the movements hereinbefore described are carried out in reverse.

When the engine 5 is loaded, however, the speed is decreased momentarily which causes a decrease in the centrifugal force causing the governor Weights 46 to move inwardly which allows the governor spring 52 to urge the sleeve member 5 1 to the left causing the fulcrum lever 57 to tilt counterclockwise about pin 59, simultaneously moving the control rod 61 to the left to increase the fuel delivery. The leftward movement is terminated at the instant the cam 63 of the fulcrum lever 57 engages the stop plate 72. The fuel control linkage is so adjusted that the cam 63 engages the stop plate 72 at the normal full load of the engine.

It is common practice in many diesel engine applications to occasionally overload the engine. Under overload conditions the engine Will tend to lose speed and finally stall should the overload become severe enough. It is well known in the art that under an overload condition, it is possible for a diesel engine to efiiciently burn an additional amount of fuel due in part to the increased volume etficiency at a reduced engine speed which results in an increase in the torque output of the engine thereby improving its lugging power. An overload is placed upon the diesel engine in many different ways depending upon the particular application.

In an engine used in a crawler tractor having a hydraulic system for operating a front end shovel attachment there are several load demands placed upon the engine. The following are examples of the principal horsepower requirements: power to drive the various engine accessories such as fan, generator, supercharger fuel pump, lubrication oil pump, water pump etc; power to propel the weight of the vehicle; power to operate the hydraulic pump supplying demands of the hydraulic system; and power to pull the drawbar load or propel the vehicle against a resistance, the drawbar load and the demands of the hydraulic system being variable while the other horsepower requirements are for the most part constant. A common belt or net horsepower rating for a diesel engine used in this type of application is about 57 horsepower (the horsepower requirements of engine driven auxiliary equipment having been deducted). About 12 horsepower is required to propel the weight of the tractor under normal operation which leaves a net of 45 horsepower available at the drawbar and to drive the hydraulic pump. When the hydraulic system is fully loaded, the hydraulic pump will require about 35 horsepower to meet the maximum demand thereby leaving only horsepower available at the drawbar. In operation, this means that the engine will be momentarily overloaded when it is desired to lift a full load with the shovel requiring 35 horsepower, simultaneously as the tractor is propelled forward against a resistance such as the material being lifted or excavated which requires more than the 10 horsepower available. Under such an overload condition the fuel injection system operates as follows: to raise the shovel, fluid must be forced into the bottom end of the hydraulic jacks 14. To accomplish this the control valve mechanism 21 is opened allowing hydraulic fluid to be delivered by the pump 27 into the cylinders 14 through conduits 29 and 31. The pressure in conduit 29 will correspond to the pressure required in the jacks 14 in order to extend the rams 114 so as to raise the load. The horsepower demand placed on the engine 5 by the hydraulic pump 27 will thus correspond to the pressure required by jacks It will also be apparent that the operation of hydraulic jacks 19 will place a load upon the hydraulic pump in a similar manner. The pressure sensing means 73 is in fluid communication through conduit 97 wth the hydraulic system 24 at a point on the delivery side of pump 27. Spring 107 is so selected that it will be overcome by a predetermined pressure demand of the pump 27 which may tend to overload the engine and which will be effective to force pin 109 left against head 103 thereby moving the stop member 101 to the left against screw 111. Under overload this leftward movement of the stop member 101 will allow the sleeve member 51 and fulcrum lever 57 to be moved to the left by the governor springs 52 simultaneously permittingadditional movement of the control rod 61 to the left so as to allow an additional quantity of fuel to be delivered to the engine by the fuel pump. This additional fuel will tend to increase the torque output of the engine thereby increasing the horsepower available at either the drawbar or the hydraulic pump.

Considering the embodiment of the invention illustrated herein from a general point of view it will be noted that hydraulic jacks 14 and 19 and shovel 7 comprise a hydaulically operated tractor tool; that the jacks serve as a pair of actuator means for the vehicle mounted tractor shovel 7; and further that the pressure sensing means 73, stop member 101 and linkage means 56 serve as a means associated with the control rod 61 and responsive to a predetermined pressure in the tractor tool for permitting additional movement of the control rod to allow an increased quantity of fuel to be delivered to the engine. In other words this device in etfect anticipates a condition which may tend to place an overload upon the engine. 7

It will be apparent from the drawings and the foregoing detailed description that a novel construction and design for a fuel regulating device has been illustrated which will permit a more rapid response and a greater power increase from the engine under overload conditions. It will also be seen that this invention differs from conventional devices in that it accomplishes delivery of additional fuel to minimize an overload condition byla device which is directly responsive to the load requirement. This is done by using the pressure rise in the hydraulically operated tractor tool to actuate the fuel regulating device and does not depend upon engine control.

It should be understood that although the particular forms and details described herein illustrate theuse of the invention in a centrifugal type flyball governor for a plunger type fuel pump on an engine for a tractor shovel loader, it is not intended to limit the patent granted hereon otherwise than is necessitated by the scope of the appended claims.

What is claimed is:

1. In a fuel injection system for the engine of a tractor vehicle of the type having a hydraulic motor system including an engine driven pump and a hydraulic motor for operating a tractor mounted tool, a fuel regulating device comprising: a movable control lever for adjusting the quantity of fuel to be delivered to the engine by the fuel injection system; an engine speed sensing means for adjusting said control lever to automatically main tain constant engine speed; a stop member for restricting movement of said control lever thereby limiting the maximum quantity of fuel to be delivered to the engine; and a pressure sensitive means associated with said stop member and responsive to a predetermined high pressure in said hydraulic motor system to adjust said stop member thereby permitting said control lever to increase the quantity of fuel to be delivered to the engine, said predetermined high pressure being directly, and solely brought about by the load on said tractor mounted tool.

2. In a fuel injection system for the engine of a tractor vehicle of the type having a hydraulic motor system in- "for"operatingatractor'rnounted toolya fuel regulating devic'e' comprisiugz a control lever movable in one direc- "t ionj to increase and in the opposite direction to decrease the quantity of'fuel delivered to the'engine by the'fuel injection system; an engine'speed sensing means in motion'transmitting relationship with said control lever for automatically maintaining constant engine speed;a 'stop "member for restricting movement of said control lever in :said one direction, thereby limitingthe maximum quan- "tity of fuel to be delivered to the'engine; and a pressure sensitive means associated with said stop member and being in fluid communication with and responsive to a predetermined high pressure in said hydraulic motor system to adjust said stop member for permitting additional movement of said control lever in said one direction, said predetermined high pressure being directly and solely brought about by the load on said tractor mounted tool.

3. In a fuel injection system for the'cngine of a tractor vehicle of the type having a hydraulic motor'system including an engine driven pump anda hydraulic motor for operating a tractor mounted tool, a fuel regulating device comprising: a movable control lever for adjusting the quantity of fuel to be delivered to the engine by the fuel 'injection system; an engine speed sensing means in motion transmitting relationship with said 'control lever for automatically maintaining constant engine speed; a stop member engageable by said speed sensing means to re strict movement 'of said control lever thereby limiting the maximum quantity of fuel to be delivered to the engine; and a pressure sensitive means connected in motion transmitting relationship with said stop member and being i in fluid communication with and responsive to a predetermined high pressure in said hydraulic motor system to adjust said stop member thereby permitting said con- "trol lever to increase the quantity of fuel to be delivered to the engine, said predetermined high pressure being directly and solelybrought about by the load on said tractor mounted tool.

4. In a fuel injection system for the engine of a tractor vehicle of the type' having a hydraulic motor system including an engine 'driven pump and a hydraulic motor for operating a tractor mounted tool, a fuel regulating device comprising: a control lever movable in one direction to increase and in the opposite direction to decrease the quantity of fuel delivered to the engine by the fuel injection system; an engine speed sensing means in motion "transmitting relationship with said control lever for auto- "matically maintaining constant engine speed; a stop member engageable by said sensing means for restricting movement of said control lever in said one direction, thereby limiting the maximum quantityof fuel to be delivered to the engine; and a pressure sensitive means connected in motion transmitting relationship with said stop member and being in fluid communication with and responsive to 'a predetermined high pressure in said hydraulic motor system to move said stop member a predetermined distance for permitting additional movement of said control lever in said one direction, said predetermined high pressure being directly and solely brought about by the load on said tractor mounted tool.

5. In a fuel injection system for the engine of a tractor vehicle of the type having a hydraulic motor system including an engine driven pump and a hydraulic motor for operating a tractor mounted tool, a fuel regulating device comprising: a control lever movable in one direction, to increase and in the opposite direction to decrease the quantity of fuel delivered to the engine by the fuel injection system; an engine speed sensing means including a link member pivotally attached in motion transmitting relationship with said control lever for automatically maintaining constant engine speed; a stop member'en- 'gageable by said link member for restricting movement of said control lever in said one direction, thereby limiting the maximum quantity of fuel to be delivered to the ""engine; and' a pressure sensitive means connected inmotion"trainsrnitting i'elationship with saidstep inenib'efand being in -fiuid'communidation with and responsive to 'a predetermined highp'ressure insaidhydraulic motorsystem to move said stopmerriber'a predetermined distance 'fo'r'permitting additional movement of said control lever in said one direction, said predetermined high pressure being directly and solely brought about by'the load on said tractor mounted tool.

6. In a fuel injection system for the engine of a tractor vehicle of the type having a hydraulic motor system including an engine driven pump anda hydraulic motor for operatinga tractor mounted tool, a fuel regulating device comprising: a control lever movable longitudinally in one -direction, to increaset and in the opposite direction to gageable by said one end of said link member forrestricting movement of said control lever in said one direction, thereby limiting the maximum quantity of fuel to be delivered to the engine; and a pressure sensitive means connected in longitudinal motion transmitting relation- "ship withsaid stop member and being in fluid communicationwithand responsive to a predetermined high pressure in said hydraulic motor system to move saidstop member a predetermined distance for permitting additional rnovement of said control lever in said one direction,"said predetermined highpressure being directly and solely broughtabout by the load on said'tractor mounted tool.

7. In a fuel injection systemfor" the engine of a'tractor'vehicleof the type having a'hydraulicmotorsystem including an engine driven'pump and a hydraulic motor foroperating a tractor mounted tool, a fuel regulating device comprising: an engine speed governor; a link member connected in thrust transmitting relationship with said governor; a fuel control lever pivotally connected tdSaidlink member; a'stop member engageable by said link member for restricting movement of said control lever thereby limiting the maximum quantity of fuel to be delivered to the engine; and a pressure sensitive means associated with said stop member and being in fluid communication with and responsive to a predetermined high pressure in said hydraulic motor system to adjust said stop member a predetermined distance thereby permitting additional movement of said control lever to increase the quantity of fuel to be delivered to the engine, said predetermined high pressure being directly and solely brought about by the load on said tractor mounted tool.

8. In a fuel injection system {for the engine of a tractor vehicle of the 'type having a hydraulic motor"sys'te"m including'an engine drivenpump and a hydraulic 'mo't'or for operating 'a 'tractormounted tool, a fuelregulating device comprising: an "engine speed governor; linkage means'including a"'fuel control lever connected in thrust transmitting relationshipwith said governor for automatically controlling the'q'uantity of fuel being delivered to the engine,'said control'lever movable in one direction 'toin'cr'ease andin the opposite direction to decrease the quantity "of fuel delivered 'to the engine; a stopmember "engageable by said linkage means tolim'it movement of said control lever in said'one direction; a'pressure'scnsitivemeans in fluid communication with said hydraulic motor system and in' thnist'transmitting relationship 'with "saids'top'member, said pressure sensing'means being re- "sponsive to a predetermined high pressure Within said hydraulic motor system to displace said stop membera predetermined distance thereby allowing additional movement of said control lever in said one direction, said predetermined high pressure being directly and solely brought about by'the load'on said tractor mounted tool.

9. 'I'he'combi'nation" set forth in claim 8 in which the pressure sensing means includes a housing; a pressure cylinder on said housing in fluid communication with said hydraulic motor system; a piston element reciprocally mounted in said cylinder and being urged in one direction by pressure in said hydraulic motor system.

10. The combination set forth in claim 9 in which a stop member is reciprocally mounted on said housing in thrust transmitting relationship with said piston element; resilient means biasing said stop member in a direction opposing movement of said piston.

11. The combination set forth in claim 10 in which said resilient means include a spring, a predetermined pressure in said hydraulic motor system being effective to overrule said spring.

12. In a fuel injection system for the engine of a tractor vehicle of the type having a hydraulic motor system for operating a tractor mounted tool, a fuel regulating device comprising: a movable control member for adjusting the quantity of fuel to be delivered to the engine by the fuel injection system; an engine speed sensing means for adjusting said control member to automatically maintain constant engine speed; and means associated with said control member including a pressure sensitive means being responsive to a predetermined high pressure in said hydraulic motor system to permit an adjustment of said control member in order to increase the maximum quantity of fuel to be delivered to the engine, said predeter' mined high pressure being directly and solely brought about by the load on said tractor mounted tool.

References Cited in the file of this patent UNITED STATES PATENTS 1,117,263 Shute Nov. 17, 1914 1,561,773 Carpenter Nov. 17, 1925 2,529,437 Weinberger Nov. 7, 1950 2,811,265 Wagner Oct. 29, 1957 FOREIGN PATENTS 408,760 Great Britain Apr. 19, 1934 432,839 Great Britain Aug. 2, 1935 1,144,626 France Apr. 29, 1957 

